The present invention relates to a method for manufacturing a thin-film magnetic head and a manufacturing system of the thin-film magnetic head.
In fabricating a thin-film magnetic head, a wafer with a large number of thin-film magnetic head elements is cut into rows so that a plurality of magnetic head sliders are sequentially coupled or aligned therein, and then each bar is processed for various works. In such working processes of each bar, it may be necessary to refer data inherent to the bar.
For example, control of a properties-determining height of a magnetoresistive effect (MR) heat element (hereinafter called as MR height), which control is necessary for fabricating a thin-film magnetic head with the MR head element, is carried out by lapping an air bearing surface (ABS) of each bar. During the lapping of the ABS, the MR height is monitored by an electrical signal from a lapping control sensor called as a RLG (Resistance Lapping Guide) or ELG (Electric Lapping Guide) sensor to correct the bending of the bar and to control the stop position of lapping, so as to obtain optimum properties of the MR head element. In order to execute such process using the RLG (or ELG) sensors, data inherent to the respective bars such as RLG center data which are different for the respective bars are required.
However, according to the conventional bar working process, data inherent to bars of each wafer are described on an independent recording paper, and this paper is transferred to the next process together with the wafer (workpiece), as described in, for example, Japanese unexamined patent publication No. 9(1997)-73615.
Thus, the workpieces have to be transferred from one working process to next working process in a unit of wafer causing dwell time between the processes to increase. Furthermore, since each bar is visually identified and also identification signals or identifiers are manually input into a working machine, identification of the bar may take much time and incorrect bar working processes may be executed due to using of another bar data.
It is therefore an object of the present invention to provide a method for manufacturing a thin-film magnetic head and a manufacturing system of the thin-film magnetic head, whereby dwell time between working processes can be reduced.
It is another object of the present invention to provide a method for manufacturing a thin-film magnetic head and a manufacturing system of the thin-film magnetic head, whereby the bar identification is certainly and easily carried out to improve the yield ratio.
According to the present invention, a method for manufacturing a thin-film magnetic head includes a step of cutting a wafer into bars, each bar having a plurality of thin-film magnetic head sliders which are sequentially coupled with each other, a step of identifying the bar to be worked to generate an identification signal which indicates identity of the bar, a step of obtaining data of the bar in a unit of bar depending upon the identification signal, and a step of processing at least one working of the bar on the basis of the obtained data of the bar.
Since the data of bars are extracted in a unit of bar, movement of bars from one process to another process can be performed by the unit of bar. As a result, each process can be smoothly carried out causing dwell time between the processes to reduce. Furthermore, workings of the bars obtained from one wafer can be simultaneously performed in parallel.
It is preferred that the data obtaining step includes a step of extracting the data from a table which stores retrievable relationships of identification signals and data of bars in a unit of bar.
It is also preferred that the bar identifying step includes a step of identifying a jig or a transfer tool to which the bar is attached. Although it is considerably difficult to identify a bar from bars themselves because of its small identification sign, it is comparatively easy to identify the jig itself to which the bar is attached. Thus, identification of bars to be worked will become sure and easy, whereby the problem according to the conventional art that incorrect bar working processes are executed due to using of another bar data can be solved.
The bar identifying step may include a step of identifying the bar by using a table which stores relationships of identifiers of bars and identifiers of jigs to which the respective bars are attached. By using such a reference table, identification of bars in each working process can be certainly and rapidly performed.
The jig identifying step may include a step of identifying the jig by using a bar code provided on the jig. If the bar code is used as the identification sign, reading of the sign can be further surely performed than in a case where other identification sign is used.
It is preferred that the processing step includes a height control step of controlling properties of the thin-film magnetic head by lapping an ABS of a slider of the thin-film magnetic head, and that the obtained data include data used in the height control step.
In this case, the height control step includes a step of measuring resistance values which vary by the lapping, a step of calculating a properties-determining height of the magnetic head from the ABS, for example MR height or throat height etc., on the basis of the measured resistance values, and a step of comparing the calculated height with a target height. The obtained data include data used in the calculating step.
It is also preferred that the thin-film magnetic head has a taper portion, that the processing step includes a taper working step of lapping the taper portion, and that the obtained data include data of a chamfer length used in the taper working step.
According to the present invention, a system for manufacturing a thin-film magnetic head includes a unit for cutting a wafer into bars, each bar having a plurality of thin-film magnetic head sliders which are sequentially coupled with each other, a unit for identifying the bar to be worked to generate an identification signal which indicates identity of the bar, a unit for obtaining data of the bar in a unit of bar depending upon the identification signal, and a unit for processing at least one working of the bar on the basis of the obtained data of the bar.
Since the data of bars are extracted in a unit of bar, movement of bars from one process to another process can be performed by the unit of bar. As a result, each process can be smoothly carried out causing dwell time between the processes to reduce. Furthermore, workings of the bars obtained from one wafer can be simultaneously performed in parallel.
It is preferred that the data obtaining unit includes a unit for extracting the data from a table which stores retrievable relationships of identification signals and data of bars in a unit of bar.
It is also preferred that the bar identifying unit includes a unit for identifying a jig to which the bar is attached. Although it is considerably difficult to identify a bar from bars themselves because of its small identification sign, it is comparatively easy to identify the jig itself to which the bar is attached. Thus, identification of bars to be worked will become sure and easy, whereby the problem according to the conventional art that incorrect bar working processes are executed due to using of another bar data can be solved.
The bar identifying unit may include a unit for identifying the bar by using a table which stores relationships of identifiers of bars and identifiers of jigs to which the respective bars are attached. By using such a reference table, identification of bars in each working process can be certainly and rapidly performed.
The jig identifying unit may include a unit for identifying the jig by using a bar code provided on the jig. If the bar code is used as the identification sign, reading of the sign can be further surely performed than in a case where other identification sign is used.
It is preferred that the processing unit includes a height control unit for controlling properties of the thin-film magnetic head by lapping an ABS of a slider of the thin-film magnetic head, and that the obtained data include data used by the height control unit.
In this case, the height control unit includes a unit for measuring resistance values which vary by the lapping, a unit for calculating a properties-determining height of the magnetic head from the ABS on the basis of the measured resistance values, and a unit for comparing the calculated height with a target height. The obtained data include data used by the calculating unit.
It is preferred that the thin-film magnetic head has a taper portion, that the processing unit includes a taper working unit for lapping the taper portion, and that the obtained data include data of a chamfer length used by the taper working unit.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.